Processors are at the heart of most computing systems. Whether a computing system is a desktop computer, a laptop computer, a communication system, a television, etc., processors are often the fundamental building block of the system. These processors may be deployed as central processing units, as memories, controllers, etc.
As computing systems advance, the power of the processors driving these computing systems increases. The speed and power of the processors are achieved by using new combinations of materials, such as silicon, germanium, etc., and by populating the processor with a larger number of circuits. The increased circuitry per area of processor as well as the conductive properties of the materials used to build the processors result in the generation of heat. Further, as these computing systems become more sophisticated, several processors are implemented within the computing system and generate heat. In addition to the processors, other systems operating within the computing system may also generate heat and add to the heat experienced by the processors.
A range of adverse effects result from the increased heat. At one end of the spectrum, the processor begins to malfunction from the heat and incorrectly processes information. This may be referred to as computing breakdown. For example, when the circuits on a processor are implemented with digital logic devices, the digital logic devices may incorrectly register a logical zero or a logical one. For example, logical zeros may be mistaken as logical ones or vice versa. On the other hand, when the processors become too heated, the processors may experience a physical breakdown in their structure. For example, the metallic leads or wires connected to the core of a processor may begin to melt and/or the structure of the semiconductor material (i.e., silicon, germanium, etc.) itself may breakdown once certain heat thresholds are met. These types of physical breakdowns may be irreversible and render the processor and computer system inoperable and unrepairable.
A number of approaches have been implemented to address processor heating. Initial approaches focused on air-cooling. These techniques may be separated into 3 categories: 1) cooling techniques which focused on cooling the air outside of the computing system; 2) cooling techniques that focused on cooling the air inside the computing system; and 3) a combination of the cooling techniques (i.e., 1 and 2).
Many of these conventional approaches are elaborate and costly. For example, one approach for cooling air outside of the computing system involves the use of a cold room. A cold room is typically implemented in a specially constructed data center, which includes air conditioning units, specialized flooring, walls, etc., to generate and retain as much cooled air within the cold room as possible.
Cold rooms are very costly to build and operate. The specialized buildings, walls, flooring, air conditioning systems, and the power to run the air conditioning systems all add to the cost of building and operating the cold room. In addition, an elaborate ventilation system is typically also implemented and in some cases additional cooling systems may be installed in floors and ceilings to circulate a high volume of air through the cold room. Further, in these cold rooms, computing equipment is typically installed in specialized racks to facilitate the flow of cooled air around and through the computing system. However, with decreasing profit margins in many industries, operators are not willing to incur the expenses associated with operating a cold room. In addition, as computing systems are implemented in small companies and in homes, end users are unable and unwilling to incur the cost associated with the cold room, which makes the cold room impractical for this type of user.
The second type of conventional cooling technique focused on cooling the air surrounding the processor. This approach focused on cooling the air within the computing system. Examples of this approach include implementing simple ventilation holes or slots in the chassis of a computing system, deploying a fan within the chassis of the computing system, etc. However, as processors become more densely populated with circuitry and as the number of processors implemented in a computing system increases, cooling the air within the computing system can no longer dissipate the necessary amount of heat from the processor or the chassis of a computing system.
Conventional techniques also involve a combination of cooling the air outside of the computing system and cooling the air inside the computing system. However, as with the previous techniques, this approach is also limited. The heat produced by processors has quickly exceeded beyond the levels that can be cooled using a combination of the air-cooling techniques mentioned above.
Other conventional methods of cooling computing systems include the addition of heat sinks. Very sophisticated heat sink designs have been implemented to create heat sinks that can remove the heat from a processor. Further, advanced manufacturing techniques have been developed to produce heat sinks that are capable of removing the vast amount of heat that can be generated by a processor. However, in most heat sinks, the size of the heat sink is directly proportional to the amount of heat that can be dissipated by the heat sink. Therefore, the more heat to be dissipated by the heat sink, the larger the heat sink. Certainly, larger heat sinks can always be manufactured; however, the size of the heat sink can become so large that heat sinks become infeasible.
Refrigeration techniques and heat pipes have also been used to dissipate heat from a processor. However, each of these techniques has limitations. Refrigeration techniques require substantial additional power, which drains the battery in a computing system. In addition, condensation and moisture, which is damaging to the electronics in computing systems, typically develops when using the refrigeration techniques. Heat pipes provide yet another alternative; however, conventional heat pipes have proven to be ineffective in dissipating the large amount of heat generated by a processor.
In yet another approach for managing the heat issues associated with a processor, designers have developed methods for controlling the operating speed of a processor to manage the heat generated by the processor. In this approach, the processing speed is throttled based on the heat produced by the processor. For example, as the processor heats to dangerous limits (i.e., computing breakdown or structural breakdown), the processing speed is stepped down to a lower speed.
At the lower speed, the processor is able to operate without experiencing computing breakdown or structural breakdown. However, this often results in a processor operating at a level below the level that the processor was marketed to the public or rated. This also results in slower overall performance of the computing system. For example, many conventional chips incorporate a speed step methodology. Using the speed step method, a processor reduces its speed by a percentage once the processor reaches a specific thermal threshold. If the processor continues to heat up to the second thermal threshold, the processor will reduce its speed by an additional 25 percent of its rated speed. If the heat continues to rise, the speed step methodology will continue to reduce the speed to a point where the processor will stop processing data and the computer will cease to function.
As a result of implementing the speed step technology, a processor marketed as a one-gigahertz processor may operate at 250 megahertz or less. Therefore, although this may protect a processor from structural breakdown or computing breakdown, it reduces the operating performance of the processor and the ultimate performance of the computing system. While this may be a feasible solution, it is certainly not an optimal solution because processor performance is reduced using this technique. Therefore, thermal (i.e., heat) issues negate the tremendous amount of research and development expended to advance processor performance.
In addition to the thermal issues, a heat dissipation method and/or apparatus must be deployed in the chassis of a computing system, which has limited space. Further, as a result of the competitive nature of the electronics industry, the additional cost for any heat dissipation method or apparatus must be very low or incremental.
Thus, there is a need in the art for a method and apparatus for cooling computing systems. There is a need in the art for a method and apparatus for cooling processors deployed within a computing system. There is a need in the art for an optimal, cost-effective method and apparatus for cooling processors, which also allows the processor to operate at the marketed operating capacity. There is a need for a method or apparatus used to dissipate processor heat which can be deployed within the small footprint available in the case or housing of a computing system, such as a laptop computer, standalone computer, cellular telephone, etc.